Measuring systems often comprise and/or interface with numerous sensors, several and/or each of which can substantially simultaneously output, provide, and/or transmit a signal indicative of a value of a detected and/or measured physical parameter, such as a position, temperature, pressure, flowrate, voltage, current, etc. Such sensor signals can be received by a receiver such as a data logger, and embedded system, a microcontroller, and/or an automated monitoring and/or control system, such as a programmable logic controller (PLC). To manage a potentially large number of incoming sensor signals, such measuring systems and/or receivers can utilize multiplexing (and/or de-multiplexing), such as time-division multiplexing, frequency-division multiplexing, and/or wave-division multiplexing, etc., to extract each sensor signal from its respective time slice, frequency, wavelength, channel, sub-channel, etc.
From the receiver's perspective, there is a possibility that a received sensor signal indicates a parameter value that is inaccurate and/or other than what was output and/or transmitted, potentially even if the received value is within a range of expected, reasonable, and/or valid values for that sensor's parameter. Such anomalies can occur because of a fault, such as a break in a wire or conductor, corrosion-generated high resistance in a conductor and/or junction, an induced voltage and/or current due to a neighboring conductor and/or magnetic field, multiple sensors connected to a conductor intended for a single sensor, ground faults due to failures in conductor insulation, arc faults, poor insulation, poor shielding, etc. Thus, it can be desirable to test the sensor circuit to detect if a fault is occurring.
To detect certain faults, a measuring system can utilize a stimulus circuit that can apply a stimulus, bias, and/or voltage to the sensor circuit, either continuously or in a pulsed manner, which can force the received and/or input sensor signal to a known “invalid” state and/or value if a fault occurs. The application of a constant stimulus, however, can add a constant error and/or distortion to the received signal. The application of a pulsed stimulus can cause time-varying perturbations to the received signal, which can corrupt logged data and/or make data analysis more difficult. Even if the perturbations are allowed to dissipate, the pulsed stimulus can add considerable additional time to the multiplexed scan time for each channel and/or sub-channel. Hence, improved systems, methods, and/or devices for detecting circuit faults, such as sensor circuit faults, is disclosed.